The present invention relates to power transmission apparatus and, more particularly, to a swivel joint for a heavy duty working vehicle, such as a crane, for simultaneously transmitting different forms of energy between a mobile carrier and a pedestal mounted thereon.
Heavy duty working vehicles such as a crane generally comprise a mobile carrier and a pedestal or superstructure carried thereby for rotation about a vertical axis. The pedestal and carrier each carry various types of power actuated mechanisms. For example, the pedestal typically carries a boom with hydraulic cylinders for adjusting the elevation thereof, a hoist motor for winding-up and paying-out cable which passes around sheaves on the boom, and a motor for rotating the pedestal. The carrier typically carries wheels with power steering and power braking mechanisms, and a transmission for conducting traction power to the wheels.
These mechanisms utilize different forms of energy which are generated by an engine, mounted on either the carrier or pedestal. Energy is transmitted to the other unit through a swivel joint connected therebetween in a manner permitting the pedestal to rotate without interferring with the transmission of energy. Exemplary of swivel joints are those described in U.S. Pat. No. 2,254,192 issued to White on Aug. 26, 1941 and U.S. Pat. No. 2,281,288 issued to Hettelsater on Apr. 28, 1942 which are designed to transmit fluid and mechanical power between a mobile carrier and pedestal.
There remains significant room for improvement in the design of swivel joints, especially as regards their versatility and size. That is, it is desirable that a swivel joint be able to simultaneously transmit electrical energy as well as fluid and mechanical energy. It is also desirable that a swivel joint be durable, relatively compact in size, and easily assembled and disassembled to facilitate maintenance. Swivel joints heretofore proposed exhibit definite shortcomings in this regard. For example, swivel joints have been previously proposed which include mechanical gearing, but no provision for lubrication thereof, thereby adversely affecting the life span of the joint.
It is, therefore, an object of the present invention to provide a novel swivel joint which obviates or minimizes problems of the types discussed above.
It is another object of the invention to provide a novel swivel joint capable of simultaneously transmitting mechanical, fluid, and electrical energy.
It is a further object of the invention to provide a novel swivel joint in which lubrication is continuously supplied to mechanically rotating elements.
It is an additional object of the invention to provide a novel swivel joint which is relatively compact in size and can be easily assembled and disassembled.